{"@context":{"@vocab":"https://cir.nii.ac.jp/schema/1.0/","rdfs":"http://www.w3.org/2000/01/rdf-schema#","dc":"http://purl.org/dc/elements/1.1/","dcterms":"http://purl.org/dc/terms/","foaf":"http://xmlns.com/foaf/0.1/","prism":"http://prismstandard.org/namespaces/basic/2.0/","cinii":"http://ci.nii.ac.jp/ns/1.0/","datacite":"https://schema.datacite.org/meta/kernel-4/","ndl":"http://ndl.go.jp/dcndl/terms/","jpcoar":"https://github.com/JPCOAR/schema/blob/master/2.0/"},"@id":"https://cir.nii.ac.jp/crid/1360574096589398656.json","@type":"Article","productIdentifier":[{"identifier":{"@type":"DOI","@value":"10.1029/93rs01579"}},{"identifier":{"@type":"URI","@value":"https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1029%2F93RS01579"}},{"identifier":{"@type":"URI","@value":"https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/93RS01579"}}],"dc:title":[{"@value":"Experimental evidence for the formation and entry of patches into the polar cap"}],"description":[{"type":"abstract","notation":[{"@value":"<jats:p>A mechanism for the formation of polar cap patches is proposed based on data collected by the Sondrestrom incoherent scatter radar, magnetometers located on the west and east coasts of Greenland and Digisondes, digital ionospheric sounders, operated at Qaanaaq and Sondrestrom. This instrumentation has served to identify the formation of patchlike structures and follow their temporal evolution and entry into the polar cap. Prior to the onset of the event, the background ionospheric plasma was moving in a poleward direction and formed part of a tongue of ionization directed toward and into the polar cap. The event starts with the appearance of a fast plasma jet containing eastward directed velocities in excess of 2 km s<jats:sup>−1</jats:sup>. This plasma jet consists of a channel extending 300 km in width, where the <jats:italic>F</jats:italic> region ion temperature reaches values in excess of 4000 K and the <jats:italic>E</jats:italic> layer <jats:italic>T<jats:sub>i</jats:sub></jats:italic> is enhanced above 5000 K. The existence of a region containing high electron temperatures associated with soft precipitation (likely the cusp) and located adjacent and equatorward of the fast plasma jet is very suggestive of the jet being the result of a tension force acting upon recently reconnected field lines. This view is supported by the fact that the fast plasma jet was seen in the prenoon sector under IMF <jats:italic>B<jats:sub>y</jats:sub></jats:italic> negative conditions. The elevated <jats:italic>T<jats:sub>i</jats:sub></jats:italic> values inside the plasma jet are exactly collocated with depleted <jats:italic>F</jats:italic> region densities. We suggest that the recombination loss of O<jats:sup>+</jats:sup> is increased by a factor >10 due to the dependence of the O<jats:sup>+</jats:sup> + N<jats:sub>2</jats:sub> reaction on the ion temperature. The eroding action of the fast plasma jet proceeds until the poleward moving tongue of ionization is divided into regions containing high and low densities. Magnetic field perturbations associated with the fast plasma jet were observed by the different magnetometer stations. The large negative bays recorded at most of the sites have been used to trace the poleward motion of the jet. At the time that the fast plasma jet reaches Qaanaaq, the Digisonde there measured low ƒ<jats:sub>0</jats:sub><jats:italic>F</jats:italic><jats:sub>2</jats:sub> values. A few minutes before and after this minimum, high ƒ<jats:sub>0</jats:sub><jats:italic>F</jats:italic><jats:sub>2</jats:sub> values were observed. The ratio of the enhanced ƒ<jats:sub>0</jats:sub><jats:italic>F</jats:italic><jats:sub>2</jats:sub> values on either side of the minimum, to the minimum ƒ<jats:sub>0</jats:sub><jats:italic>F</jats:italic><jats:sub>2</jats:sub> is about 2 (or a density ratio of 4). This is the commonly accepted signature of a polar cap patch. The series of events leading to the formation of the patchlike density structure has been designated a density breakoff event.</jats:p>"}]}],"creator":[{"@id":"https://cir.nii.ac.jp/crid/1380567007825682055","@type":"Researcher","foaf:name":[{"@value":"C. E. Valladares"}]},{"@id":"https://cir.nii.ac.jp/crid/1380574096589398659","@type":"Researcher","foaf:name":[{"@value":"S. Basu"}]},{"@id":"https://cir.nii.ac.jp/crid/1380574096589398657","@type":"Researcher","foaf:name":[{"@value":"J. Buchau"}]},{"@id":"https://cir.nii.ac.jp/crid/1380016869362653568","@type":"Researcher","foaf:name":[{"@value":"E. Friis‐Christensen"}]}],"publication":{"publicationIdentifier":[{"@type":"PISSN","@value":"00486604"},{"@type":"EISSN","@value":"1944799X"}],"prism:publicationName":[{"@value":"Radio Science"}],"dc:publisher":[{"@value":"American Geophysical Union (AGU)"}],"prism:publicationDate":"1994-01","prism:volume":"29","prism:number":"1","prism:startingPage":"167","prism:endingPage":"194"},"reviewed":"false","dc:rights":["http://onlinelibrary.wiley.com/termsAndConditions#vor"],"url":[{"@id":"https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1029%2F93RS01579"},{"@id":"https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/93RS01579"}],"createdAt":"2004-02-04","modifiedAt":"2023-09-22","relatedProduct":[{"@id":"https://cir.nii.ac.jp/crid/1360004233287111552","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"Decay of polar cap patch"}]},{"@id":"https://cir.nii.ac.jp/crid/1360285704780971776","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"Periodic creation of polar cap patches from auroral transients in the cusp"}]},{"@id":"https://cir.nii.ac.jp/crid/1360285708263689088","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"Dynamic temporal evolution of polar cap tongue of ionization during magnetic storm"}]},{"@id":"https://cir.nii.ac.jp/crid/1360285708267097472","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"Periodicities of polar cap patches"}]},{"@id":"https://cir.nii.ac.jp/crid/1360294643748518144","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"Cusp Dynamics and Polar Cap Patch Formation Associated With a Small IMF Southward Turning"}]},{"@id":"https://cir.nii.ac.jp/crid/1360848665119537280","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"Direct observations of blob deformation during a substorm"}]},{"@id":"https://cir.nii.ac.jp/crid/1390282681488187264","@type":"Article","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@language":"en","@value":"Temporal and spatial variability of auroral forms in the 10-14 MLT sector: Relationship to plasma convection and solar wind-magnetosphere coupling"},{"@language":"ja-Kana","@value":"Temporal and spatial variability of aur"}]},{"@id":"https://cir.nii.ac.jp/crid/2050307417166183168","@type":"Article","resourceType":"学術雑誌論文(journal article)","relationType":["isReferencedBy"],"jpcoar:relatedTitle":[{"@value":"The science case for the EISCAT_3D radar"}]}],"dataSourceIdentifier":[{"@type":"CROSSREF","@value":"10.1029/93rs01579"},{"@type":"CROSSREF","@value":"10.1186/s40645-015-0051-8_references_DOI_JfjpmfgVDrRenZcMlVXR1FyTthv"},{"@type":"CROSSREF","@value":"10.1029/2010ja016297_references_DOI_JfjpmfgVDrRenZcMlVXR1FyTthv"},{"@type":"CROSSREF","@value":"10.1186/bf03352161_references_DOI_JfjpmfgVDrRenZcMlVXR1FyTthv"},{"@type":"CROSSREF","@value":"10.1002/2015ja022221_references_DOI_JfjpmfgVDrRenZcMlVXR1FyTthv"},{"@type":"CROSSREF","@value":"10.1029/2010ja015848_references_DOI_JfjpmfgVDrRenZcMlVXR1FyTthv"},{"@type":"CROSSREF","@value":"10.1029/2012ja018165_references_DOI_JfjpmfgVDrRenZcMlVXR1FyTthv"},{"@type":"CROSSREF","@value":"10.1029/2020ja029090_references_DOI_JfjpmfgVDrRenZcMlVXR1FyTthv"},{"@type":"CROSSREF","@value":"10.5194/angeo-33-525-2015_references_DOI_JfjpmfgVDrRenZcMlVXR1FyTthv"}]}